Induction heating lines are necessary and valuable systems to adequately prepare metal billets for subsequent metal forming or surface treating processes. Induction heating systems typically employ a transfer line beginning with a hopper where bulk, similarly shaped metal billets are deposited for transport down a process line.
Common load side material handling systems typically will first consist of a linear in feed vibratory track or chain conveyor onto which the billets will be directly loaded from a vibratory bowl feeder or hopper where a plurality of billets are deposited for processing. Exiting the bowl feeder or hopper, the billets are oriented in a single file, sequential line and typically advanced along by a linear in feed vibratory track or chain conveyor toward a variable speed, carefully controlled pinch wheel mechanism that will forcibly advance the abutting, sequentially oriented billets through a downstream induction heating coil line. Due to the weight of the billets, the pinch wheel steadily and continuously advances the billets at a rate determined by the requirements of the heating process for the billet material, size, length, and subsequent metal forming or surface treating process. The pinch wheel may automatically adjust in vertical height or clearance and rotational speed to accommodate a different diameter of billet between production runs.
Conventional induction heating coil lines often includes several self-contained modular billet heating chambers or units sequentially positioned one after another along the billet process line. The billet heating line may range in total length from about 10 feet to over 80 feet depending on the number of coils based on requirements for the heating and downstream processes. The track supporting the billets passes through a tunnel in each induction-heating unit whereby the billets are passed within proximity of the induction heating coils. The heated billets emerge from the heating coil line and typically onto a high-speed exit conveyor. As a billet exits the heating coil line, the billet is typically “broken” from the billet behind it through an extractor roll. As the billet exits the heating coil line, the billet is typically checked for temperature by means of an optical pyrometer or other temperature measuring device.
It is common for high volume metal forming businesses to change the type of billets to be transferred through the induction heating line. For example, at the end of a run of a first billet alloy or size, the manufacturer may order a second different billet alloy or size to be processed. When a changeover occurs to a billet having a different alloy or size, other parameters of the induction heating process need to be changed, for example, the rate at which the billets are advanced through the heating units may have to increase or decrease to achieve the desired heating of the billet. Alternately, the manufacturer may have to shut the line down at the end of a shift or for other reasons, such as maintenance or repair of the system.
In these instances of billet changeover or line shut down, once the last billet of the run passes through the pinch rollers, there is no longer forced advancement of the line of billets presently in the heating units. Manufactures need to exit or “clear” the line and run out all of the remaining billets in the heating unit portion of the line. Historically, manufactures used manual means, such as a long pole, to forcibly push on the last in line billet and force the preceding billets in the heating units past the exit of the last heating unit to “clear” the line. The billets inside the coils can be very heavy and be difficult to manually push. Other methods have been employed, for example, feeding wooden or “dummy” billets behind the last production billet to keep the production billets advancing through the heating units. Any stoppage or deviation from the carefully monitored advancement of the billets line inside the heating units alters the heating process and results in non-standard billets, which often require reprocessing or have to be repurposed. Even where dummy billets are used to advance the line, these dummy billets have to be cleared from the heating units through one of the means described above. Any non-standard production billets or dummy billets that need to be removed from the production billets are thermally hot having absorbed a large amount of electrical energy via induction heating and are often heavy which requires additional precautions for workers or equipment used to remove and segregate them from the processed production billets.
Automated clean-out devices have been employed, but have substantial limitations and disadvantages. In one automated clean-out device, a large spool of interlinked, chain-like, dummy billets has been employed upstream of the pinch rollers. At the end of a billet run, the spool begins to advance the linked dummy billets to advance the remaining billets through the heating units. Once the billets were cleared from the heating units, the spool would reverse and retract the interlinked dummy billets back onto the spool. These prior spool devices had many disadvantages, as they were large in size, heavy and complex in design. Further, the size of the interlinked dummy billets was fixed per spool, which may limit its use to clear only certain types of billets. Due to the size and weight of the spool, it was not feasible to change a spool to accommodate the many changes in the billet production schedule reducing usefulness and efficiency of the entire production heating line.
An automated clean-out device and method is needed to greatly improve on prior designs and provide an efficient, safe and cost effective solution for manufacturers.